A key-sharing scheme is used to control distribution and use of video and audio content in personal digital assistants (PDAs) and other wireless devices. A private key is split into key-shares using a Blakley-Shamir key splitting technique and the key-shares are distributed to various network entities including a finance server and security server. Key-shares are also stored in a user's subscriber identity module (SIM) and a security processor of the PDA. The key-shares from the network entities are provided to the PDA after the user requests specific video or audio content and a credit verification is performed. The PDA's security processor combines the key-shares to form the decryption key for use in playing the content by the PDA's communications processor. When a service limit is reached, the PDA's security processor purges the key-shares to prevent further use of the content.